'Sparkles' could be heating the Sun's atmosphere

Scientists studying images of the Sun's atmosphere captured by a
Nasa camera may have discovered why the star's atmosphere is so
much hotter than its surface.

The images were taken last July by Nasa's High Resolution
Coronal Imager (Hi-C). The results of the study are being
announced today by Professor Robert Walsh at the Royal
Astronomical Society's National Astronomy Meeting taking place this
week in St Andrews, Scotland.

The innovative camera was sent into space for just over ten
minutes. Launched aboard a Nasa suborbital sounding rocket
from the White Sands Missile Range in New Mexico on July 11 2012,
the Hi-C flight lasted 620 seconds.

Hi-C set its sights on a magnetically-active sunspot region and
snapped away every few seconds of its brief mission, capturing 165
images in the extreme ultraviolent light, the higher
energy wavelength being optimal for viewing the hot solar
corona.

The international team of scientists studying the images, led by
astronomers at the University of Central Lancashire (UCLan) in the
UK, found dynamic bright dots - dubbed 'sparkles' by the team -
which switch on and off at high speed and release huge amounts of
energy into the corona.

Each sparkle is about 680 km across and typically lasts
around 25 seconds, and releases at least 1024 (one million million
million million) Joules of energy -- about 10,000 times the yearly
energy consumption of the UK. The sparkles provide evidence
that enormous amounts of energy are being added into the corona and
may then be released violently to heat the plasma.

According to the study, these enormous releases of energy into
the corona could solve the mystery as to why the Sun's corona -- at
two million degrees Celsius -- is around 400 times hotter than
its photosphere (surface).

The study also found small clumps of electrified gas (plasma)
speeding along 'highways' in a Coronal Mass Ejection (CME). The
highways are about 450 km across and shaped by the Sun's magnetic field. These clumps
have a temperature of about one million degrees Celsius and travel
at about 80 km per second. The finding of these highways improves
our understanding of CMEs -
eruptions of bubbles of magnetic field and gas from the solar
atmosphere.

CMEs travel with speeds of up to 2,000 km per second and send
charged particles into the Solar System -- these take between 1 and
4 days to reach Earth where they can cause damage to electrical
infrastructure. CMEs can also pose a threat to satellites and
astronauts. The discovery of these solar highways will enable
scientists to understand better the driving force behind CMEs, and
improve prediction of when they might take place.

Professor Walsh, a solar physicist and Director of Research at
the University of Central Lancashire (UCLan), commented: "I'm
incredibly proud of the work of my colleagues in developing Hi-C.
The camera is effectively a microscope that lets us view small
scale events on the Sun in unprecedented detail. For the first time
we can unpick the detailed nature of the solar corona, helping us
to predict when outbursts from this region might head towards the
Earth."

The UCLan team worked with scientists from NASA and
the Lebedev Physical Institute of the Russian Academy of
Sciences in Moscow. Dr Jonathan Cirtain, senior heliophysicist
at NASA's Marshall Space Flight Center and principal
investigator for the Hi-C mission, observed: "Our team developed an
exceptional instrument capable of revolutionary image resolution of
the solar atmosphere. We took advantage of the high level of solar
activity to focus in on an active sunspot and obtained these
remarkable pictures."

Hi-C is one of a number of missions sent to explore the
Sun. NASA recently launched its latest explorer, IRIS
(Interface Region Imaging Spectrograph) which aims to further our
understanding of the Sun's surface and atmosphere.

This article originally appeared on Sen.com. For daily space news follow Sen on Twitter: @sen